1833-LB: Methylation of MicroRNAs in Human Skeletal Muscle following Acute Exercise

Introduction & Objective: MicroRNAs (miRNAs) are non-coding RNAs that act as epigenetic modulators by regulating gene expression post-transcriptionally. Given their regulatory role in gene expression, epigenetic modifications such as DNA methylation to the miRNA, may affect their expression. Previous work from our group has focused on DNA methylation of protein-coding genes, but recently, we have been exploring the methylation status of miRNAs. This study aimed to identify methylation changes in genes coding for miRNAs following a single exercise session.

Methods: We studied 14 sedentary participants (7 male/7 female): age = 34.5 ± 3.1 years, body mass index = 29.3 ± 1.9 kg/m2 and HbA1c = 5.3 ± 0.1 %. We performed VO2peak tests to determine exercise capacity (VO2peak = 25.5 ± 1.6 mL per Kg per minute) and euglycemic hyperinsulinemic clamps (Rd value = 5.9 ± 0.8 mg per Kg per minute) with vastus lateralis muscle biopsies before and 30 minutes after exercise. We extracted DNA from the muscle biopsies and performed reduced representation bisulfite sequencing followed by MethylSig analysis.

Results: An acute exercise bout resulted in 171 differentially methylated cytosines (P < 0.05 and methylation change ≥ 5%), corresponding to 110 unique miRNA genes. Among them, 101 were hypomethylated, and 70 were hypermethylated following exercise. Hypomethylated miRNAs included Hsa-mir-1225 (5 DMCs, 10-25% decrease) and Hsa-mir-3187 (8 DMCs, 6-14% decrease). Hypermethylated miRNAs included Hsa-mir-375 (2 DMCs, 15-19% increase) and Hsa-mir-1915 (3 DMCs, 14-15% decrease). Enrichment analysis of the miRNAs revealed pathways related to ECM and membrane receptors, immune responses, DNA damage responses, STAT3 signaling, and others.

Conclusion: Our study reveals that an acute exercise bout induces alterations in the DNA methylation of various genes coding for miRNAs. Additional work is needed to elucidate how these methylation alterations influence gene expression and biological pathways.